Usually conical, or, more precisely, frusto-conical, and rotatable about a vertical axis, a centrifuge screen basket, whether upright or inverted, ordinarily is fed through its smaller end with the material or mixture to be deliquefied and/or classified. In any case, it is the rotary movement of the basket imparted to it by the centrifuge and transmitted through it to the material fed into it that produces the centrifugal force responsible for the deliquefying and/or classifying of the material by driving liquid and any small particle content of the material radially outwardly through openings in the screening surface of the screen basket. Movement of the material upwardly or downwardly along the screening surface of the basket to the basket's outlet or discharge end may be produced in a continuous operation either by an independently rotatable feed screw inside the basket or and more usually by vibrating the basket horizontally or vertically.
Due to its greater strength and relative freedom from clogging, a type of conical centrifuge screen basket widely used has a screening area formed by laterally spaced, axially or longitudinally extending, wedge-shaped screen wires backed and connected externally by being welded at the back to longitudinally spaced circumferential tie bands or bars and having the inner or internal screening or flow surface of its screening areas formed by the bases or inner faces of the screen wires. If, as usual, flat and laterally disposed tangentially of the cone bounded or contained by the basket's screening surface or perpendicular or normal to a bisecting radial plane, the bases of the screen wires, when the basket is initially installed in a centrifuge, present to the material fed into the basket a smooth screening surface interrupted only by the conventionally V-shaped, outwardly flaring slots between the screen wires. Consequently, whether or not the basket is made as usual of a plurality of conical segments or panels welded together along their adjoining edges, the smooth screening surface initially presented to the material fed into the basket is inefficient or relatively ineffective in imparting rotary movement and consequent centrifugal force to the material. This condition of relative slippage of the interfaces of the basket and material will prevail, usually for several hours, until the abrasion by the material of the screening surface has roughened the latter to the point where the friction between the interfaces enables the basket to impart its rotary movement efficiently to the material. It is this condition, which heretofore has rendered centrifuge screen baskets of the welded screen wire--tie band type inefficient when initially installed, that the present invention is primarily concerned with rectifying.